While I wrote an entire book that goes into great detail about the topic, I figure it might be helpful to summarize what Scripture actually teaches about salvation and the Gospel. The following is from a Gospel tract I wrote that I like to hand out around Toronto:
Religion teaches that God will only look kindly upon us if we believe and/or do the right things before we die. The Good News of the Uncircumcision (Galatians 2:7), on the other hand, is not a religion at all, but is instead the announcement of the end of religion (it’s a proclamation, not a proposition). Religion consists of all the things (believing, behaving, worshipping, sacrificing) the religious think they have to do to get right with God, but no action or belief on our part can ever take away our sins or make us immortal. Thankfully, everything necessary for salvation from sin and death has already been done, once and for all, by Christ. The Good News (or Gospel) is that Christ died (actually died, including ceasing to exist consciously) for our (meaning everybody’s) sins, was entombed, and was roused from the dead on the third day (1 Corinthians 15:1-4). This means that sin has been completely dealt with by Christ for everybody and, because of this, everyone (1 Corinthians 15:20-28) will eventually experience salvation and be resurrected (if they’re dead) and vivified (be made immortal) by the consummation (or end) of the eons (“God is the Saviour of all mankind…”); and if God has elected to give you the gift of faith to believe this Good News now, you’ve now joined the body of Christ and will experience a special, earlier salvation known as eonian life (“…especially of believers.” 1 Timothy 4:10), meaning you’ll have immortal life in heaven (or “the heavens,” which is really just outer space — Genesis 1:1) in a glorified body like Christ’s, where you’ll help reconcile celestial beings to God during the next two eons before the rest of humanity is also vivified.
If you’d like to learn more, please check out my free eBook at https://concordantgospel.com/ebook/ where I go into much more detail on the topics of salvation and rightly dividing the word of truth.